Darius the Great (Pers. داریوش Dâriûsh, old Persian Darayavaush), the son of Hystaspes and Persian Emperor from 521 to 485 BC.

The principal source for his history is his own inscriptions, especially the great inscription of Behistun, in which he relates how he gained the crown and put down the rebellions. In modern times his veracity has often been doubted, but without any sufficient reason; the whole tenor of his words shows that we can rely upon his account. The accounts given by Herodotus and Ctesias of his accession are in many points evidently dependent on this official version, with many legendary stories interwoven, e.g. that Darius and his allies left the question as to which of them should become king to the decision of their horses, and that Darius won the crown by a trick of his groom.

Darius belonged to a younger branch of the royal family of the Achaemenidae. When, after the suicide of Cambyses II (March 521), the usurper Gaumata ruled undisturbed over the whole empire under the name of Bardiya (Smerdis), son of Cyrus, and no one dared to gainsay him. Darius, "with the help of Ahuramazda," attempted to regain the kingdom for the royal race. His father Hystaspes was still alive, but evidently had not the courage to urge his claims. Actually, according to his incription found at Susa, both his father Hystaspes and his grandfather Arsames, were alive when he became the king. Assisted by six noble Persians, whose names he proclaims at the end of the Behistun inscription, he surprised and killed the usurper in a Median fortress (October 521), and gained the crown. He also married Atossa, the widow of Smerdis.

But this sudden change was the signal for an attempt on the part of all the eastern provinces to regain their independence. In Susiana, Babylon, Media, Sagartia, and Margiana, usurpers arose, pretending to be of the old royal race, and gathered large armies around them; in Persia itself Vahyazdata imitated the example of Gaumata and was acknowledged by the majority of the people as the true Bardiya. Darius with only a small army of Persians and Medes and some trustworthy generals overcame all difficulties, and in 520 and 519 all the rebellions were put down (Babylon rebelled twice, Susiana even three times), and the authority of Darius was established throughout the empire.

Darius in his inscriptions appears as a fervent believer in the true religion of Zoroaster. He was also a great statesman and organizer. The time of conquests had come to an end; the wars which Darius undertook, like those of Augustus, only served the purpose of gaining strong natural frontiers for the empire and keeping down the barbarous tribes on its borders. Thus Darius subjugated the wild nations of the Pontic and Armenian mountains, and extended the Persian dominion to the Caucasus; for the same reasons he fought against the Sacae and other Turanian tribes. But by the organization which he gave to the empire he became the true successor of the great Cyrus. His organization of the provinces and the fixing of the tributes is described by Herodotus (iii. 90 if.), evidently from good official sources.

He fixed the coinage and introduced the gold coinage of the Daric (which is not named after him, as the Greeks believed, but derived from a Persian word meaning "gold"; in Middle Persian it is called zarig). He tried to develop the commerce of the empire, and sent an expedition down the Kabul and the Indus, led by the Carian captain Scylax of Caryanda, who explored the Indian Ocean from the mouth of the Indus to Suez. He dug a canal from the Nile to Suez, and, as the fragments of a hieroglyphic inscription found there show, his ships sailed from the Nile through the Red Sea by Saba to Persia.

He had connexions with Carthage (i.e. the Karka of the Nakshi Rustam inscription), and explored the shores of Sicily and Italy. At the same time he attempted to gain the good-will of the subject nations, and for this purpose promoted the aims of their priests. He allowed the Jews to build the Temple of Jerusalem. In Egypt his name appears on the temples which he built in Memphis, Edfu and the Great Oasis. He called the high-priest of Sais, Tzahor, to Susa (as we learn from his inscription in the Vatican), and gave him full powers to reorganize the "house of life," the great medical school of the temple of Sais.

In the Egyptian traditions he is considered as one of the great benefactors and lawgivers of the country. In similar relations he stood to the Greek sanctuaries (cf. his rescript to "his slave" Godatas, the inspector of a royal park near Magnesia, on the Maeander, in which he grants freedom of taxes and forced labour to the sacred territory of Apollo); all the Greek oracles in Asia Minor and Europe therefore stood on the side of Persia in the Persian Wars and admonished the Greeks to attempt no resistance.

About 512 Darius undertook a war against the Scythians. A great army crossed the Bosporus, subjugated eastern Thrace, and crossed the Danube. The purpose of this war can only have been to attack the nomadic Turanian tribes in the rear and thus to secure peace on the northern frontier of the empire. It was based upon a wrong geographical conception; even Alexander and his Macedonians believed that on the Hindu Kush (which they called Caucasus) and on the shores of the Jaxartes (which they called Tanais, i.e. Don) they were quite near to the Black Sea. Of course the expedition undertaken on these grounds could not but prove a failure; having advanced for some weeks into the Russian steppes, Darius was forced to return. The details given by Herodotus (according to him Darius had reached the Volga!) are quite fantastical; and the account which Darius himself had given on a tablet, which was added to his great inscription in Behistun, is destroyed with the exception of a few words.

Although European Greece was intimately connected with the coasts of Asia Minor, and the opposing parties in the Greek towns were continually soliciting his intervention, Darius did not meddle with their affairs. The Persian wars were begun by the Greeks themselves. The support which Athens and Eretria gave to the rebellious Ionians and Carians made their punishment inevitable as soon as the rebellion had been put down. But the first expedition, that of Mardonius, failed on the cliffs of Mount Athos (492), and the army which was led into Attica by Datis in 490 was beaten at Marathon. Before Darius had finished his preparations for a third expedition an insurrection broke out in Egypt (486). In the next year Darius died, probably in October 485, after a reign of thirty-six years. He is one of the greatest rulers the east has produced.